1. FIELD OF THE INVENTION
The object of the present invention is a process for fast firing of ceramic products and particularly of wall-tiles or floor-tiles or other uses.
2. DESCRIPTION OF THE PRIOR ART
The conventional process used for the production of tiles involves a double-firing process wherein the body of the tile, after having been formed by pressing the raw material, or in any other suitable way, is fired as it is and it is subsequently glazed on one of its faces and finally the glaze is fired.
The conventional process, which is used for a wide range of ceramic products, provides products of the desired quality, but it is obviously time consuming and expensive and attempts have been made to replace it with faster and cheaper processes, particularly by the so-called single firing processes in which the ceramic body is coated with the glaze after drying and subsequently the glazed body is fired in a single-phase.
The single-phase firing processes are more critical and difficult than the conventional one and have been carried out more or less successfully according to the raw materials used and the shape and nature of the required product. However, these do not always afford the desired savings, for instance in cases in which the single-firing requires a considerable length of time and produces a poor quality product or a high rate of rejects.
The relative fast single-firing is feasible, as well known in the art, by using certain raw materials, especially batches with a high content, for example 70%, of talcum and wollastonite.
However, such a method of operation is economically advantageous only in some specific areas, like the United States, but not in most areas like Europe, South America and Asia, where, for economic reasons and according to the availability of materials, there is required the use of natural clay bodies or--depending on the areas--of bodies firing with clay, kaolin, calcium or magnesium carbonates, silica and feldspathic materials and other natural components as well as pre-treated or synthetic materials.